Liquid crystal display device

ABSTRACT

A reliability of seal portion of a liquid crystal display device can be improved by the following structure. A liquid crystal display device includes: a TFT substrate which includes a display region and a terminal part, and has an inorganic insulating film formed on an organic passivation film and an alignment film formed over the inorganic insulating film; a counter substrate, the TFT substrate and the counter substrate bonded together by a sealing material formed at a seal part surrounding the display region; and a liquid crystal sealed inside. At the seal part, a transparent conductive oxide film is formed between the inorganic insulating film and the alignment film. The transparent conductive oxide film exists inside an edge of the TFT substrate and hence, the edge of the TFT substrate is free of the transparent conductive oxide film.

CLAIM OF PRIORITY

The present application claims priority from Japanese Patent ApplicationJP 2014-110118 filed on May 28, 2014, the content of which is herebyincorporated by reference into this application.

BACKGROUND

The present invention relates to a liquid crystal display device andmore particularly, to a liquid crystal display device of a narrowerframe width that can ensure reliability of a seal part.

A liquid crystal display device includes: a TFT substrate where pixelseach including a pixel electrode, a thin film transistor (TFT) and thelike are arranged in a matrix; a counter substrate opposed to the TFTsubstrate; and liquid crystal sandwiched between the TFT substrate andthe counter substrate. The liquid crystal display device forms an imageby controlling transmittance of light through liquid crystal moleculeson a per-pixel basis.

Being flat and light in weight, the liquid crystal display device hasbeen finding wider applications in various fields. Compact liquidcrystal display devices have been widely used in cellular phones, DSCs(Digital Still Cameras) and the like. Medium- and small-sized liquidcrystal display devices are faced with a strong demand for enlarging adisplay region while maintaining a small outside configuration.Accordingly, the liquid crystal display device is reduced in widthbetween an edge of the display region and an edge of the device. Namely,the device is adapted to a so-called narrow frame design. The devicehaving the narrower frame is reduced in seal width of a sealing materialbonding the TFT substrate and the counter substrate together and hence,is faced with a problem of a bonding force of the seal part.

An alignment film for initial alignment of the liquid crystal moleculesis formed on each of the surfaces of the TFT substrate and the countersubstrate, on which surfaces the TFT substrate and the counter substratemake contact with the liquid crystal. The prior-art technique hasadopted a structure where the alignment film is not formed on the sealpart in order to increase the reliability in the bonding force of theseal part. In the case of the narrow frame design, however, it isdifficult to exclude the alignment film from the seal part. To addressthe reliability in the bond of the seal part, therefore, considerationmust be given to the bond strength between the sealing material and thealignment film and the bond strength between the alignment film and anunderlying film thereof.

As a technique for preventing the rubbing off of the alignment film onprojections resulting from wiring on the display region, JapaneseUnexamined Patent Application Publication No. 2012-189856 suggests anapproach to increase the bond strength of the alignment film by applyingITO (Indium Tin Oxide) on the projections. Further, Japanese UnexaminedPatent Application Publication No. Hei 10-206871 discloses a structurewhere the wiring is formed of ITO and the ITO wiring is laid under theseal part and extended to a terminal part. Japanese Unexamined PatentApplication Publication No. Hei 10-206871 does not describe a range ofapplying the alignment film.

SUMMARY OF THE INVENTION

As to the reliability of the seal part, attention has heretofore beenpaid only to the bonding force between the sealing material and thealignment film. However, when the increase in the bonding force betweenthe sealing material and the alignment film is achieved, then bondbetween the alignment film and the underlying film thereof constitutes aproblem. The alignment film and the underlying film have been consideredin the art to have sufficient bond strength. As the frame becomesnarrower, the bonding force between the alignment film and theunderlying film thereof becomes a problem.

The underlying film of the alignment film differs between aTFT-substrate side and a counter-substrate side. In most cases, anorganic film called an overcoat film constitutes the underlying film onthe counter-substrate side while an inorganic film made of Sin or thelike constitutes the underlying film on the TFT-substrate side. Thealignment film is an organic film made of polyimide or the like. Thebond strength between the organic film and the organic film is generallystrong. However, the bond strength between the organic film and theinorganic film is comparatively weak. Therefore, the bonding forcebetween the alignment film and the underlying film poses a problem tothe TFT-substrate side.

It is an object of the present invention to increase the bond strengthbetween the organic film and the inorganic film on the TFT-substrateside in particular and to provide a liquid crystal display deviceensuring the reliability of the seal part while narrowing of the frame.

The present invention is directed to solution to the above problem andthe specific means thereof are as follows.

According to a first aspect of the present invention, a liquid crystaldisplay device includes: a TFT substrate which includes a display regionand a terminal part, and has an inorganic insulating film formed on anorganic passivation film and an alignment film formed over the inorganicinsulating film; a counter substrate, the TFT substrate and the countersubstrate bonded together by a sealing material formed at a seal partsurrounding the display region; and a liquid crystal sealed inside, and

has a structure where at the seal part, a transparent conductive oxidefilm is formed between the inorganic insulating film and the alignmentfilm, an edge of the transparent conductive oxide film exists inside anedge of the TFT substrate.

According to a second aspect of the present invention, the liquidcrystal display device according to the first aspect thereof has astructure where at the seal part, the organic passivation film is formedwith a groove-like through-hole surrounding the display region, and thetransparent conductive oxide film is formed inside than the groove-likethrough-hole.

According to a third aspect of the present invention, the liquid crystaldisplay device according to the first aspect thereof has a structurewhere the transparent conductive oxide film is made of ITO.

According to a fourth aspect of the present invention, the liquidcrystal display device according to the first aspect thereof has astructure where the transparent conductive oxide film is made of IZO.

According to a fifth aspect of the present invention, the liquid crystaldisplay device according to the first aspect thereof has a structurewhere the transparent conductive oxide film is formed on four sidessurrounding the display region.

According to a sixth aspect of the present invention, the liquid crystaldisplay device according to the first aspect thereof has a structurewhere the transparent conductive oxide film is formed on the three sidesexcept a terminal part.

According to a seventh aspect of the present invention, the liquidcrystal display device according to the first aspect thereof has astructure where the transparent conductive oxide film is continuouslyformed around the display region, and the width of an overlap betweenthe sealing material and the transparent conductive oxide film is 100 μmor more.

According to an eighth aspect of the present invention, the liquidcrystal display device according to the first aspect thereof has astructure where the transparent conductive oxide film is formed in aplurality of continuous lines surrounding the display region, and thetotal of the widths of overlaps between the sealing material and thetransparent conductive oxide film formed in the plural continuous linesis 100 μm or more.

According to a ninth aspect of the present invention, the liquid crystaldisplay device according to the first aspect thereof has a structurewhere the area of an overlap between the transparent conductive oxidefilm and the sealing material is 20% or more of the total bond area onwhich the sealing material on the TFT-substrate side is bonded to thetransparent conductive oxide film.

According to a tenth aspect of the present invention, the liquid crystaldisplay device according to the first aspect thereof has a structurewhere the alignment film contains a silane coupling agent.

According to an eleventh aspect of the present invention, the liquidcrystal display device according to the first aspect thereof has astructure where the alignment film is subjected to optical alignmentprocessing.

According to the present invention, the liquid crystal display deviceensuring the reliability of the seal part is provided because thebonding force between the alignment film and the underlying film thereofcan be ensured even in the structure where the frame is narrowed and thealignment film is applied to the seal part.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view showing a liquid crystal display device accordingto the present invention;

FIG. 2 is a sectional view taken on the line A-A in FIG. 1 for showing afirst embodiment of the present invention;

FIG. 3 is a schematic plan view of a TFT substrate corresponding to FIG.2;

FIG. 4 is a sectional view taken on the line A-A in FIG. 1 for showinganother mode of the first embodiment 1;

FIG. 5 is a sectional view taken on the line A-A in FIG. 1 for showingstill another mode of the first embodiment 1;

FIG. 6 is a sectional view taken on the line A-A in FIG. 1 for showingstill another mode of the first embodiment 1;

FIG. 7 is a sectional view taken on the line A-A in FIG. 1 for showing asecond embodiment of the present invention;

FIG. 8 is a schematic plan view of a TFT substrate corresponding to FIG.7;

FIG. 9 is a schematic plan view of a TFT substrate for showing an ITOforming range;

FIG. 10 is a schematic plan view of a TFT substrate according to anotherembodiment of the present invention for showing an ITO forming range;

FIG. 11 is a schematic plan view of a TFT substrate according to stillanother embodiment of the present invention for showing an ITO formingrange;

FIG. 12 is a schematic plan view of a TFT substrate according to stillanother embodiment of the present invention for showing an ITO formingrange;

FIG. 13 is a schematic plan view of a TFT substrate according to stillanother embodiment of the present invention for showing an ITO formingrange;

FIG. 14 is a schematic plan view of a TFT substrate according to stillanother embodiment of the present invention for showing an ITO formingrange;

FIG. 15 is a schematic plan view of a TFT substrate according to stillanother embodiment of the present invention for showing an ITO formingrange;

FIG. 16 is a schematic plan view of a TFT substrate according to stillanother embodiment of the present invention for showing an ITO formingrange;

FIG. 17 is a schematic plan view of a TFT substrate according to stillanother embodiment of the present invention for showing an ITO formingrange;

FIG. 18 is a schematic plan view of a TFT substrate according to stillanother embodiment of the present invention for showing an ITO formingrange;

FIG. 19 is a schematic plan view of a TFT substrate according to stillanother embodiment of the present invention for showing an ITO formingrange; and

FIG. 20 is a sectional view taken on the line A-A in FIG. 1.

FIG. 21 is a sectional view taken on the line A-A in FIG. 1 according toanother mode of the present invention.

DETAILED DESCRIPTION

Before describing specific embodiments of the present invention, a briefdescription is made on a structure of a liquid crystal display device.FIG. 20 is a sectional view showing an example of a seal part of theliquid crystal display device. Referring to FIG. 20, liquid crystal 300is sandwiched between a TFT substrate 100 and a counter substrate 200.An alignment film 106 is formed on each of the surfaces of the TFTsubstrate 100 and the counter substrate 200, on which surfaces the TFTsubstrate 100 and the counter substrate 200 make contact with the liquidcrystal 300. At a narrow frame, the alignment film 106 is extended to aseal part, where the TFT substrate 100 and the counter substrate 200 arebonded together by a sealing material 30. The prior-art techniques haveaddressed the bond strength between the sealing material 30 and thealignment film 106. As the frame becomes narrower, however, bondstrength between the alignment film 106 and an underlying film thereofis considered as a problem. On the TFT-substrate 100 side, inparticular, the problem is the bonding force between the alignment film106 and an inorganic insulating film 104 which is formed of SiN or thelike as the underlying film of the alignment film.

On the other hand, a so-called viewing angle means much to the liquidcrystal display. The IPS (In Plane Switching) system has excellentcharacteristics in the viewing angle. Alignment processing for thealignment film 106 includes a conventional rubbing method and aso-called optical alignment method which produces uniaxial anisotropy inthe alignment film by irradiating the alignment film with polarizedultraviolet rays. In the IPS system, the optical alignment method ismore suitable because the method negates the need for inducingliquid-crystal pretilt angle on the alignment film 106.

The alignment film 106 is irradiated with the ultraviolet rays in theoptical alignment processing, which involves a fear that the ultravioletrays may reach an interface between the alignment film 106 and the SiNfilm 104 as the underlying film thereof, inducing a decrease in thebonding force. Therefore, the problem of bonding force between thealignment film 106 and the underlying film 104 can be more critical inthe IPS system.

The present invention to be described hereinbelow is directed tosolution to the above problem. The contents of the present inventionwill be specifically described as below with reference to embodimentsthereof.

First Embodiment

FIG. 1 is a plan view showing a liquid crystal display device to whichthe present invention is applied. Referring to FIG. 1, the TFT substrate100 and the counter substrate 200 are bonded together by the sealingmaterial 30 while the liquid crystal is sandwiched between the TFTsubstrate 100 and the counter substrate 200. The TFT substrate 100 isformed in a larger size than the counter substrate 200. A portion of theTFT substrate 100 that extends as a single layer defines a terminal part150. The terminal part 150 is formed with an IC driver 160 for driving aliquid crystal display panel, terminals for connection of a flexiblewiring board for supplying electric power, image signals, scan signalsand the like to the liquid crystal display panel, and the like.

Referring to FIG. 1, a display region 1000 includes scanning lines 10extended horizontally and arranged vertically, and further includesimage signal lines 20 extended vertically and arranged horizontally. Anarea enclosed by the scanning line 10 and the image signal line 20defines a pixel 25. At the narrow frame, a distance w between an edge ofthe display region 1000 and an edge of the liquid crystal display deviceis reduced to the order of 1 mm. In this case, the device can allow forno more than 0.5 mm of bond width for the sealing material 30, whichmakes the bond strength at the seal part a crucial matter.

FIG. 2 is a detailed sectional view of the seal part, corresponding to across section taken on the line A-A in FIG. 1. Referring to FIG. 2, afirst insulating film 101 is formed on the TFT substrate 100 made ofglass. The first insulating film 101 may sometimes be an undercoat filmformed for preventing a semiconductor layer of the TFT from beingcontaminated with impurities from the glass. A second insulating film102 is formed on the first insulating film 101. The second insulatingfilm 102 may sometimes be a gate insulating film of the TFT. On thesecond insulating film 102, the scanning lines 10 and scanning-line leadlines 11 are formed. The rectangular scanning-line lead line 11represents a cross section of the scanning-line lead line 11 extendedfrom an upper side as seen in the drawing of FIG. 1.

An organic passivation film 103 is overlaid on the scanning lines 10 andthe scanning-line lead lines 11. The passivation film 103 is formedthick or 2 to 3 μm in thickness and also serves as a flattening film.The passivation film 103 is formed of a photosensitive resin, negatingthe need for photoresist when patterned.

An interlayer insulating film 104 made of SiN is overlaid on the organicpassivation film 103. In the display region of the IPS liquid crystaldisplay device, this interlayer insulating film 104 is an insulatingfilm between a lower layer electrode formed in a flat solid layer and anupper layer electrode including slits. The lower layer electrode may bea common electrode while the upper layer electrode may be a pixelelectrode, and vice versa. Both the lower layer electrode and the upperlayer electrode are formed of a transparent conductive oxide film 105represented by ITO (Indium Tin Oxide). While the following descriptionis made on the assumption that the transparent conductive oxide film 105is made of ITO, the transparent conductive oxide film 105 may sometimesbe made of IZO (Indium Zinc Oxide).

Referring to FIG. 2, the ITO 105 is formed on the interlayer insulatingfilm 104, which constitutes a feature of the present invention. This ITO105 is at least insulated from the ITO of the pixel electrodes in thedisplay region 1000. However, the ITO 105 is formed in conjunction withthe formation of the upper layer electrode in the display region.

The alignment film 106 is overlaid on the ITO 105. The bonding forcebetween the alignment film 106 and the ITO 105 is so strong that thebond strength between the alignment film 106 and the ITO 105 can beensured despite the narrow seal width. Although the bonding forcebetween the alignment film 106 and the ITO 105 also means much to otherparts, the bonding force particularly constitutes a crucial problem tothe seal part, where stress occurs between the sealing material 30 andthe alignment film with the ITO.

In a case where the alignment film 106 includes a silane coupling agent,the bonding force between the alignment film 106 and the ITO 105 can befurther increased. This is because an OH-group of the alignment film 106is strongly bonded to an OH-group of the ITO 105. Incidentally, the ITO105 is also strongly bonded to the interlayer insulating film 104 as theunderlying film thereof which is made of SiN. Since the ITO 105 does notextend so far as an edge of the TFT substrate 100, there is no fear ofinvasion of moisture through an interface between the ITO 105 and otherlayers in contact therewith.

The alignment film 106 is formed by applying an alignment film materialas a starting liquid by flexography, ink-jet printing or the like. Theorganic passivation film 103 is formed with recesses 65, 66, 67 as astopper for preventing the alignment material from spreading so far asan outside edge of the seal part. Further, a groove-like through-hole 60formed on an even outer side of the recesses also serves as the stopperfor the alignment film material. FIG. 2 shows the alignment filmmaterial spreading beyond the three recesses 65, 66, 67 and ending atthe groove-like through-hole 60 as the final stopper.

Referring to FIG. 2, a black matrix 201 is formed on thecounter-substrate 200 side. The black matrix 201 in FIG. 2 is disposedfor preventing light leakage from the seal part 30. The black matrix 201is formed of a resin and hence, the black matrix is formed with a blackmatrix groove 2011 for blocking moisture permeation through the resin.On the black matrix 201, a color filter 202 is formed in a strip patternextended in a direction perpendicular to the drawing surface. The colorfilter 202 is formed in correspondence to a column-like spacer 40 formedon an overcoat film 203.

The overcoat film 203 is formed on the color filter 202. The overcoatfilm 203 is formed with protrusions at places corresponding to the colorfilter 202. This protrusion has a function to prevent the alignment filmmaterial being applied from spreading toward the outside of thesubstrate. A first column-like spacer 40 is formed at the protrusion ofthe overcoat film 203. The first column-like spacer 40 has a function todefine a distance between the counter substrate 200 and the TFTsubstrate 100 at the seal part. Between the first column-like spacer 40and the first column-like spacer 40, a second column-like spacer 45which has a smaller height than the first column-like spacer 40 isformed. The second column-like spacer 45 has a function to prevent thedistance between the TFT substrate 100 and the counter substrate 200from being excessively reduced when an external pressure is applied tothe counter substrate 200.

The alignment film 106 is overlaid on the overcoat film 203. A wall-likespacer 50 is formed at an end of the seal part. The wall-like spacer 50is placed on a boundary between adjoining liquid crystal display panelson a mother substrate where a plurality of liquid crystal display panelsare formed. Scribing is performed along the center of the wall-likespacer 50, followed by separating the individual liquid crystal displaypanels by breaking the mother substrate. The reason for locating thewall-like spacer at this portion is that the mother substrate cannot bebroken despite the scribing performed on the spacer if the sealingmaterial 30 exists at this portion. Referring to FIG. 2, the sealingmaterial 30 is present in a slight gap between the wall-like spacer 50and the TFT-substrate 100 side. However, this sealing material does notaffect the breaking operation significantly so long as the thickness ofthe sealing material in this gap is 1 μm or less. In some cases, thesealing material 30 having a thickness of 1 μm or less may contribute tobonding between the counter substrate 200 and the TFT substrate 100.

Referring to FIG. 2, the alignment film 106 formed on thecounter-substrate 200 side extends beyond the protrusions formed on theovercoat film 203 and ends at the wall-like spacer 50. On thecounter-substrate 200 side, the alignment film 106 is formed on theovercoat film 203. Both the overcoat film 203 and the alignment film 106are formed of organic materials. The bonding force between the organicmaterials is so strong that the bonding force between the alignment film106 and the overcoat film 203 does not matter much.

At the seal part, the TFT substrate 100 and the counter substrate 200are bonded together by the sealing material 30. Although the sealingmaterial 30 is bonded to the alignment films 106 as seen in FIG. 2, thebond between the sealing material 30 and the alignment films 106 can bepractically maintained. In FIG. 2, the liquid crystal 300 is filled inspace inside the sealing material 30.

FIG. 3 is a plan view of the TFT substrate 100 shown in FIG. 1 and FIG.2. FIG. 3 is a schematic diagram showing relationships among the sealpart, the display region 1000, the interlayer insulating film 104, thegroove-like through-hole 60 and the ITO 105. Referring to FIG. 3, anarea outside a dotted line 31 defines the seal part where the sealingmaterial is formed. Around the display region, the ITO 105 is formed andits outside is surrounded by the groove-like through-hole 60, externalto which is the interlayer insulating film 104 covering the organicpassivation film.

The alignment film 106 covers the display region 1000 and an areabetween the display region 1000 and the groove-like through-hole 60. Atthe seal part, the alignment film 106 is formed on the ITO 105. Thebonding forces between the ITO 105 and the alignment film 106 andbetween the ITO 105 and the interlayer insulating film 104 made of SiNare strong enough. Therefore, the alignment film 106 at the seal partshown in FIG. 3 has high reliability in bonding. Further, the ITO 105does not extend so far as the edge of the TFT substrate 100 and hence,there is no fear of moisture invading from the edge of the TFT substrate100 through the interface of the ITO 105.

FIG. 4 is a sectional view showing another mode of this embodiment. FIG.4 differs from FIG. 2 in that the organic passivation film 103 of theTFT substrate 100 is not formed with the recesses. As shown in FIG. 4,the alignment film 106 ends at the groove-like through-hole 60 of theorganic passivation film 103. As seen in FIG. 4 as well, the ITO 105 isformed between the interlayer insulating film 104 and the alignment film106 and hence, the bond performance of the alignment film 106 can beensured. Further, the ITO 105 does not extend so far as the edge of theTFT substrate 100 and hence, there is no fear of moisture invading fromthe edge of the TFT substrate 100 through the interface of the ITO 105.

FIG. 5 is a sectional view showing still another mode of thisembodiment. FIG. 5 differs from FIG. 2 in that the overcoat film 203 onthe counter-substrate 200 side is formed with a groove 70. This groove70 is formed in a configuration to surround the display region 1000. Theovercoat-film groove 70 has the same function as that of the groove-likethrough-hole 60 formed in the organic passivation film 103 on the TFTsubstrate 100. Namely, this groove blocks the external moisture invadingthrough the overcoat film 203.

As seen in FIG. 5, the alignment film 106 ends at the overcoat-filmgroove 70. Further, the sealing material 30 is also filled in theovercoat-film groove 70. The other components are the same as those ofthe FIG. 2 and the effects thereof are also the same as those of FIG. 2.

FIG. 6 is a sectional view showing still another mode of thisembodiment. FIG. 6 differs from FIG. 5 in that the alignment films 106are not extended to the vicinity of the edge of the sealing material 30but ends at some point short of the edge of the sealing material. In acase where the bond between the sealing material 30 and the alignmentfilm 106 is somewhat weak, the mode shown in FIG. 6 is better adapted toincrease the reliability of the seal part.

Referring to FIG. 6, the alignment film 106 on the TFT-substrate 100side ends at the third recess 67 while the alignment film on thecounter-substrate 200 side ends at the second protrusion from thedisplay region. On the TFT-substrate 100 side, the sealing material 30is bonded to the alignment film 106, the ITO 105, and the interlayerinsulating film 104. On the counter-substrate 200 side, the sealingmaterial 30 is bonded to the alignment film 106, and the overcoat film203. The bond strength between the sealing material 30 and the ITO 105,the bond strength between the sealing material and the interlayerinsulating film 104, and the bond strength between the sealing material30 and the overcoat film 203 are greater than the bond strength betweenthe sealing material 30 and the alignment film 106.

As described above, this embodiment is adapted to prevent the separationof the alignment film 106 at the seal part on the TFT-substrate 100 sideand hence, can increase the reliability of the seal part.

Second Embodiment

FIG. 7 is a sectional view showing as second embodiment of the presentinvention. FIG. 7 is a sectional view also corresponding to thesectional view taken on the line A-A in FIG. 1. FIG. 7 differs from FIG.2 of the first embodiment in that the ITO 105 formed on theTFT-substrate 100 side does not extend so far as an inside edge of thesealing material 30. In this case, as well, the ITO 105 exists betweenthe alignment film 106 and the interlayer insulating film 104 at a mainportion of the sealing material 30 and hence, the separation of thealignment film 106 at the seal part 30 can be prevented. The othercomponents in FIG. 7 are the same as those of FIG. 2.

FIG. 8 is a plan view of the TFT substrate 100 corresponding to thestructure of FIG. 7, or a schematic diagram showing relationships amongthe display region 1000, the range of the ITO 105, the interlayerinsulating film 104, the groove-like through-hole 60 and the like.Referring to FIG. 8, an area outside the dotted line 31 defines the sealpart where the sealing material 30 is formed. The ITO 105 extends withina range of the width of the sealing material 30 but not so far as theinside edge of the sealing material 30.

The range of applying the alignment film 106 is the whole area that isinside the groove-like through-hole 60 formed in the organic passivationfilm 103 and that includes the display region 1000. This embodiment isalso adapted to prevent the separation of the alignment film because ata major part with respect of the seal width, the ITO 105 is disposedbetween the alignment film 106 and the interlayer insulating film 104.Similarly to the first embodiment, therefore, this embodiment is alsoadapted to increase the reliability of the seal part.

FIG. 21 is another sectional view corresponding to the sectional viewtaken on the line A-A in FIG. 1. FIG. 21 differs from FIG. 7 in that thealignment film 106 is formed until the edge of the TFT substrate 100 andthe counter substrate 200. In FIG. 21, the ITO 105 exists between thealignment film 106 and the interlayer insulating film 104 at a mainportion of the sealing material 30 and hence, the separation of thealignment film 106 at the seal part 30 can be prevented, even thealignment film 106 is formed until the edge of the TFT substrate 100.Manufacturing becomes much easier if imitation of alignment film 106 isnot necessary.

In FIG. 21, the alignment film 106 on the counter substrate 200 isformed until the edge of the counter substrate 200, however, thealignment film 106 on the counter substrate 200 can be stopped before itextends to the edge of the counter substrate 200 in a manner as depictedin FIGS. 2, 4-7.

In FIG. 21, ITO 105 doesn't extends so far as an inside edge of thesealing material 30, however, ITO 105 can extends beyond the inside edgeof the sealing material 30 in a manner as depicted in FIG. 2, 4-6. ThirdEmbodiment

FIG. 9 to FIG. 19 each show an example of the range of forming the ITO105 on the TFT substrate 100 according to the present invention. In eachof the drawings, the alignment film 106 is formed on the whole area thatis inside the groove-like through-hole 60 formed in the organicpassivation film 103 and that includes the display region 1000. However,the alignment film 106 may also be formed on the whole area of the TFTsubstrate 100, the area including the seal part. Further, in the rangeof an overlap between the alignment film 106 and the sealing material30, an outside edge of the alignment film 106 may sometimes be locatedinside the groove-like through-hole 60 of the organic passivation film103. In all the examples, however, the ITO 105 is formed in the rangethat is inside the groove-like through-hole 60 formed in the organicpassivation film 103. That is, the ITO 105 is formed inside the outsideedge of the sealing material 30.

FIG. 9 shows an example where the range of applying the ITO 105 isdivided into two line portions and the inside edge 31 of the sealingmaterial 30 is formed on the inner ITO 105. In this case, a part of thesealing material 30 is bonded to the interlayer insulating film 104 butthe greater part of the sealing material 30 overlaps with the ITO 105.Therefore, the separation of the alignment film at the seal part can beprevented and the bond strength of the seal part can be ensured.

It is desirable that the range where the ITO 105 overlaps with thesealing material 30 is 100 μm or more in terms of width. In the casewhere the range of the overlap between the ITO 105 and the sealingmaterial 30 is divided into two line portions as shown in FIG. 9, thetotal of the two line portions of the ITO 105 may be defined to be 100μm or more. The same also applies to a case where the ITO includes threeor more portions.

FIG. 10 shows an example where the ITO 105 is formed in a plurality ofislands rather than in a continuous configuration. Referring to FIG. 10,while the sealing material 30 may have the inside edge located at anyplace, the range of the overlap between the sealing material 30 and theITO 105 may preferably be defined to be 20% or more of the bond area ofthe sealing material 30.

FIG. 11 shows an example where the ITO 105 is formed in a frame-likeconfiguration, each side of which includes a gap extended toward theoutside of the TFT substrate. The ITO may sometimes be laid out as shownin FIG. 11 due to wiring reasons or the like. In this case, as well, thearea of the overlap between the ITO 105 and the sealing material 30 maybe defined to be 20% or more of the bond area of the sealing material30.

FIG. 12 shows an example where the ITO 105 has three sides configuredthe same way as in FIG. 3 except for one side abutting on the terminalpart 150, or the ITO 105 is not formed on the side abutting on terminalpart 150. The lead lines of the image signal lines 20, scanning lines 10and the like are concentrated on the terminal-part 150 side, where itmay sometimes be difficult to form the ITO 105 over the interlayerinsulating film 104 due to layout reasons. On the other hand, the sealpart on the terminal-part 150 side permits the frame to be formed widerthan the seal parts on the other three sides. With the increased sealwidth and production tolerance taken into account, an overlap betweenthe seal part and the alignment film can be omitted. In some cases, theseal part can ensure the bonding force if the ITO 105 is not provided onthe terminal-part 150 side. FIG. 13 and FIG. 14 each show an exemplarymodification of the range of removing the ITO 105 from the terminal-part150 side. The modifications have the same effect as that described withreference to FIG. 12.

FIG. 15 shows an example where the ITO 105 has the three sidesconfigured the same way as in FIG. 8 except for the one side abutting onthe terminal part 150, or the ITO 105 is not formed on the side abuttingon the terminal part 150. FIG. 16 and FIG. 17 each show an exemplarymodification of the range of removing the ITO 105 from the terminal-part150 side. The modifications have the same effect as that described withreference to FIG. 12.

FIG. 18 shows an example where the ITO 105 is formed in two lines on thethree sides around the display region 1000 except for the terminal-part150 side, similarly to the layout shown in FIG. 9, and on theterminal-part 150 side, only the inner ITO line 105 is overlapped withthe sealing material 30. In FIG. 18, the scanning lines 10 and the outerITO line 105 are not extended in parallel with the terminal-part 150side but extended to the edges of the interlayer insulating film 104.FIG. 19 shows an exemplary modification where only the inner ITO line105 is overlapped with the sealing material 30 on the terminal-part 150side while the outer ITO line 105 is not extended to the edges of theinterlayer insulating film 104 on the terminal-part 150 side.

While the various examples of the ranges of forming the ITO 105 havebeen described above, what is common to the examples is that in the caseof the ITO 105 formed around the display region 100, the width of theoverlap between the ITO 105 and the sealing material 30 is 100 μm ormore and that in the case of the ITO 105 not formed in the continuousconfiguration, the area of the overlaps between the ITO 105 and thesealing material 30 is 20% or more of the bond area of the sealingmaterial 30. It is noted here that the term “the bond area of thesealing material 30” means the area on which the sealing material 30 onthe TFT-substrate 100 side is bonded to the ITO. In the case where aplurality of annular ITOs 105 are formed and the plural ITOs 105 overlapwith the sealing material 30, the common feature is that the total ofthe widths of overlaps between the plural ITOs 105 and the sealingmaterial 30 is 100 μm or more.

According to the above description, the ITO 105 as the transparentconductive oxide film 105 is formed between the interlayer insulatingfilm 104 and the alignment film 106. The ITO 105 can be formed inconjunction with the formation of the pixel electrodes or commonelectrodes made of ITO on the display region. In the case where thepixel electrodes or the common electrodes are made of IZO, however, thetransparent conductive oxide film 105 formed between the interlayerinsulating film 104 and the alignment film 106 may be made of IZO.

According to the present invention as described above, the separation ofthe alignment film at the seal part can be prevented and hence, theliquid crystal display device having the narrower frame can ensure thereliability of the seal part. When the optical alignment processing isperformed on the alignment film of the IPS system, the bonding forcebetween the alignment film and the underlying film thereof is decreased.Therefore, the present invention is particularly effective in the IPSsystem using the optical alignment.

What is claimed is:
 1. A liquid crystal display device comprising: a TFT substrate which includes a display region and a terminal part, and has an inorganic insulating film formed on an organic passivation film and an alignment film formed over the inorganic insulating film; a counter substrate, the TFT substrate and the counter substrate bonded together by a sealing material formed at a seal part surrounding the display region; and a liquid crystal sealed inside, wherein at the seal part, a transparent conductive oxide film is formed between the inorganic insulating film and the alignment film, and an edge of the transparent conductive oxide film exists inside an edge of the TFT substrate.
 2. The liquid crystal display device according to claim 1, wherein at the seal part, the organic passivation film is formed with a groove-like through-hole surrounding the display region, and the transparent conductive oxide film is formed inside than the groove-like through-hole.
 3. The liquid crystal display device according to claim 1, wherein the transparent conductive oxide film is made of ITO.
 4. The liquid crystal display device according to claim 1, wherein the transparent conductive oxide film is made of IZO.
 5. The liquid crystal display device according to claim 1, wherein the transparent conductive oxide film is formed on four sides surrounding the display region.
 6. The liquid crystal display device according to claim 1, wherein the transparent conductive oxide film is formed on the three sides except a terminal part.
 7. The liquid crystal display device according to claim 1, wherein the transparent conductive oxide film is continuously formed around the display region, and the width of an overlap between the sealing material and the transparent conductive oxide film is 100 μm or more.
 8. The liquid crystal display device according to claim 1, wherein the transparent conductive oxide film is formed in a plurality of continuous lines surrounding the display region, and the total of the widths of overlaps between the sealing material and the transparent conductive oxide film formed in the plural continuous lines is 100 μm or more.
 9. The liquid crystal display device according to claim 1, wherein the area of an overlap between the transparent conductive oxide film and the sealing material is 20% or more of the total bond area on which the sealing material on the TFT-substrate side is bonded to the transparent conductive oxide film.
 10. The liquid crystal display device according to claim 1, wherein the alignment film contains a silane coupling agent.
 11. The liquid crystal display device according to claim 1, wherein the alignment film is subjected to optical alignment processing. 